WHEEL-BEARERS 



287 



slightly widening at the mouth, is affixed by the lower 

 extremity to the slender filaments of water-grass, crow- 

 foot, etc. It is about one fifty-fifth of an inch in length, 

 pellucid but tinged with brownish yellow. It appears to 

 be of a gelatinous texture, and is covered with extraneous 

 substances, such as decaying animal or vegetable matters, 

 which adhere to its surface. From the mouth of the tube 

 protrudes a transparent colorless animal, the 

 head of which is rounded, with the extrem- 

 ity pursed up. Suddenly it unfolds its 

 flower-like wheel, which consists of two broad 

 nearly circular lobes united, the margin of 

 which is set with strong cilia, much resem- 

 bling those of the last species. Each cilium 

 appears to be curved, and to be thickened 

 at the middle the optical expression of the 

 ciliary wave; and the effect of the rotation, 

 as each seems to pursue its fellows around 

 the circular course down the dividing sinu- 

 osity, on the opposite sides, and around the 

 margin again, is very striking. The cilia at 

 the front are interrupted between the lobes. 

 In the centre of each lobe is a broad plate, 



111 , . -I - .. TWO-LIFPED TUBE*- 



surrounded by a bright nng, and crossed WHEEL. 

 by radiating lines which also extend toward the ciliated 

 margin; probably these are muscular filaments. The fun- 

 nel is between the lobes, and leads by a short oesophagus 

 to a bulbous transparent mastax, in which are seen jaws 

 that work on each other. Below this is a long capacious 

 sac, without convolutions or constrictions, but apparently 

 granular in its texture. The alimentary canal is bent up- 

 ward through the whole length, terminating in an orifice 



